Sentinel lymph node procedure leads to upstaging of patients with resectable colon cancer: results of the Swiss prospective, multicenter study sentinel lymph node procedure in colon cancer.

Background: The value of the sentinel lymph node (SLN) procedure in colon cancer patients remains a matter of debate. The objective of this prospective, multicenter trial was 3-fold: to determine the identification rate and accuracy of the SLN procedure in patients with resectable colon cancer; to evaluate the learning curve of the SLN procedure; and to assess the extent of upstaging due to the SLN procedure.

Methods: One hundred seventy-four consecutive colon cancer patients were enrolled onto this prospective trial. They underwent an intraoperative SLN procedure with isosulfan blue 1% injected peritumorally followed by open standard colon resection with oncologic lymphadenectomy. Three levels of each SLN were stained with hematoxylin and eosin (H&E) and immunostained with the pancytokeratin marker AE1/AE3 if H&E was negative.

Results: SLN identification rate and accuracy were 89.1% and 83.9%, respectively. SLN were significantly more likely to contain tumor infiltrates than non-SLN (P < 0.001). Both SLN identification rate (P = 0.021) and the sensitivity of the procedure (P = 0.043) significantly improved with experience. The use of immunohistochemistry in SLN resulted in an upstaging of 15.4% (16 of 104) stage I and II patients considered node-negative in initial H&E analysis.

Conclusions: The SLN procedure for colon cancer has good identification and accuracy rates, which further improve with increasing experience. Most importantly, the SLN procedure results in upstaging of >15% of node-negative patients. The potential advantage of performing the SLN procedure appears to be particularly important in these patients because they may potentially benefit from adjuvant therapy.